Recently, systems for automatically starting vehicle engines have been proposed and practically used, examples of which are disclosed in Japanese Unexamined Patent Publications No. 2002-221132 and No. 2005-248859.
Specifically, such an engine automatic starting system installed in a vehicle is operative to communicate by radio with a mobile device of the vehicle's user to authenticate whether the vehicle's user is validated.
When it is authenticated that the vehicle's user is validated, and it is determined that a starter switch of the vehicle is in on state, the engine automatic starting system automatically drives a starter motor of an engine until air-fuel mixture fed into the combustion chamber of a cylinder of the engine allows complete combustion to take place.
As compared with a manual engine starter system that drives the starter motor while the starter switch is in on state, the engine automatic starting system can eliminate the need for the user to continue manual operations for engine starting until air-fuel mixture fed into the combustion chamber of a cylinder of the engine allows complete combustion to take place. This makes it possible to improve the salability of vehicles installing the engine automatic starting system, and to prevent the starter motor from being driven when it is not needed, such as while the vehicle is moving.
In the engine automatic starting system, when the starter switch is turned off before it is authenticated that the vehicle's user is validated, it may be determined that requirements for automatically starting the engine are not satisfied. This is because the on state of the starter switch is one of the requirements for automatically starting the engine. Thus, when it is determined that the requirements are not satisfied due to the off state of the starter switch, engine automatic starting cannot be performed.
Especially, the problem probably tends to take place when a unit for communicating with a mobile device and a unit for executing the automatic starting operations are individually provided in an engine automatic starting system.
Specifically, as the unit for communicating with a mobile device, an immobilizer is normally installed in advance in a vehicle. The immobilizer is operative to store therein a unique ID (identifier) of the vehicle beforehand, receive an ID wirelessly transmitted from a mobile device, compare the ID stored therein with the received ID, and determine that the mobile device (the user thereof) is validated when the comparison result represents that both IDs are matched with each other.
As the unit for executing the automatic starting operations, an engine ECU (electronic control unit) for controlling the engine is installed in advance in the vehicle. The engine ECU is communicably coupled to the immobilizer via an in-vehicle local area network (LAN), such as a CAN (Controller Area Network). The engine ECU is operative to communicate with the immobilizer in encrypted form via the in-vehicle LAN to thereby receive the comparison result (authentication result) therefrom. This increases the delay time from start of the wireless communication between the immobilizer and the mobile device to completion of the validation determination by the engine ECU, which may cause the starter switch to be turned off before the validation determination is completed (see FIG. 8B).
Note that, as illustrated in FIG. 8A, in the manual engine starter system working to drive the starter motor during on state of the starter switch, even though the delay time is increased, a vehicle's user consciously keeps the starter switch on until cranking is started so that air-fuel mixture fed into the combustion chamber of a cylinder of the engine allows complete combustion to take place (t10 in FIG. 8A). For this reason, the increase of the delay time may not cause serious problems in the manual engine starter system.
In contrast, as illustrated in FIG. 8B, in the engine automatic starting system, even though the engine ECU determines that the validation result is proper (t12 in FIG. 8A), when the determination is carried out after the starter switch is turned off (t11 before t10 in FIG. 8B), the engine ECU cannot drive the starter motor.